计算具有相同值的行数

Question

I have the following tables:

Table A:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   ID  |   User    |   Enterpr_id    |
|   1   |   test1   |      1          |
|   2   |   test2   |      2          |
|   3   |   test3   |      3          |
|   4   |   test4   |      4          |
|   5   |   test5   |      1          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Table B:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   Enterpr_id    |     Name    |
|   1             |   Nespresso |
|   2             |     what    |
|   3             |     else    |
|   4             |     need    |
|   5             |     help    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

I have a foreign key on Enterpr_id with Table A, how can I make a count alternate and get the expected Output:

Nespresso - 2 users
what - 1 user
else - 1 user
need - 1 user
help - 0 user

Answer 1

That's a simple join:

select a.user, b.name
from tablea a
inner join tableb b on b.entrepr_id = a.entrepr_id

---

Edit : from your updated question, you seem to want aggregation and a left join :

select b.name, count(a.id) cnt_users
from tableb b
left join tablea a on a.entrepr_id = b.entrepr_id 
group by b.entrepr_id, b.name
order by b.entrepr_id 

Answer 2

It's a left join query with a count:

SELECT Name, COUNT(TableA.ID)
FROM TableB LEFT JOIN TableA ON TableB.Enterpr_id = TableA.Enterpr_id
GROUP BY TableB.Enterpr_id, TableB.Name;